A year after the Beslan school siege bloodbath many questions remain unanswered - angering the victims' relatives and fuelling rumours of a Russian cover-up.

How did dozens of gunmen - allegedly driving on a truck laden with explosives - manage to dodge checkpoints dotted around North Ossetia's borders?

Why did negotiations with the militants - demanding a pullout of Russian troops from Chechnya - fail?

Who is to blame for the first explosion in the school's gym - with more than 1,000 people in it - that led to the assault by Russian troops?

And why did the troops fire tank shells and flame-throwers - a move many in Beslan believe resulted in the deaths of 331 people?

So far, the trial of the allegedly sole surviving hostage-taker and a separate parliamentary inquiry - both ongoing - have failed to explain the chain of events during those three tragic days.

We need to look him (Mr Putin) in the eyes and tell him that he is
responsible for the deaths of our children

Susanna DudiyevaBeslan Mothers Committee

Some people in Beslan are blaming directly President Vladimir Putin and other top officials for failing to protect them and also for not investigating the tragedy properly.

"The authorities are not interested in telling us the truth, because it would show that the system is guilty," said Susanna Dudiyeva, who heads the Beslan Mothers Committee.

Meeting some of the mothers on Friday, President Putin pledged that the investigation would not gloss over any official incompetence.

Fresh controversy was sparked by a recent statement attributed to the self-confessed mastermind of the siege, Chechen warlord Shamil Basayev, claiming that Russian security services had allowed the gunmen safe passage.

Prosecutors' version

Prosecutors at the trial of alleged hostage-taker Nur-Pashi Kulayev say 32 gunmen drove in an army truck from neighbouring Ingushetia, seizing the school on 1 September.

Mr Kulayev denies the charges of murder and terrorism

They say the gunmen brought all the weapons and home-made explosives with them.

After protracted negotiations, special forces had no choice but to storm the gym when one of the bombs accidentally went off and gunfire was heard in the gym, the prosecutors say.

They say the commandos took all possible precautions to save the hostages' lives, but heavy casualties occurred when the gym's roof collapsed, after being blown up by the attackers.

Mr Kulayev was the only hostage-taker who managed to escape, according to the prosecutors.

The assertions of this terrorist and child-murderer (Shamil Basayev) are total nonsense

Gen Nikolai ShepelRussian deputy chief prosecutor

Separately, the parliamentary commission looking into the actions of Russian officials during the siege has interviewed hundreds of witnesses.

The commission is yet to publish its findings, but its head Alexander Torshin recently admitted that the overall picture of the inquiry still had "many holes".

Several former hostages and relatives of the Beslan victims have been questioning the prosecution's main assumptions.

Beslan mothers are determined to find the truth

They say a cache of weapons had been hidden under the school's floors in advance.

They also claim more than 32 gunmen took part in the siege and that some of them managed to escape.

The testimony of Mr Kulayev - who in May pleaded not guilty to all nine charges against him - also significantly differed from the version presented by the prosecutors.

The 24-year-old Chechen carpenter said the first blast happened after a sniper killed one of the hostage-takers, who was holding a detonator.

Several survivors testified that just before the explosion they saw one of the gunmen controlling the detonator slumping off the chair.

And under pressure from the victims' relatives, Russian deputy chief prosecutor Gen Nikolai Shepel admitted earlier this year that troops did use flame-throwers, following initial denials by the military.

But Gen Shepel said the troops did not use incendiary napalm grenades. Russian officials also insist that the tank shells were fired not at the gym.

'Double agent'

In the statement posted on a rebel website, Shamil Basayev claimed that Russian security services bore responsibility for the siege.

Basayev - Russia's most wanted man - said a security service agent had been sent undercover to the rebels to persuade them to carry out an attack in North Ossetia's capital, Vladikavkaz.

The warlord said the agent then made a confession, allowing the rebels to plan an alternative strike in Beslan.

He said the gunmen were allowed to enter the region with ease, because security services planned to capture them in Vladikavkaz.

Basayev also claimed that another attacker had survived the siege and was now with the rebels.